Grinding machine



Oct. 6, 1931. H. E. KEMP-TON E1' M .v

@BINDING MACHINE Filed .June 22l 1925 A10 Sheets-Sheet 2 .Muth/ Gall/Imam,

UCL 5 1931. H. E. KEMPTO ET Al.. 1,823,178

GRINDING- MACHINE Filed June 22l 1925 1o Smets-sheet 3 @MAM M @ZM Get. 6, 1931. H. E. KEMPTON ET AL GRINDING MACHINE Filed June 22. 1925 10 Sheets-Sheet 4 @CL 5, @3L H. E. KEMPTON ET AL. @$255378 GRINDING MACHINE Filed June 22, 1925 l0 Sheets-Sheet 5 H. E. KEMPTON ET AL GRINDING MACHINE @i 6, wsa.

Filed June 22, '1925 1o sheetsneet 6 Lemma 10 Sheets-Sheet 7 H. E. KEMPTON ET AL GRINDING MACHINE Filed June 22, 1925 @et 6.. w31.

@et 6, @EL "H. E. KEMPTON ET AL g GRINDING MACHINE Filed June 22, 1925 l0 Sheets-Sheet 8 {l z5 1,74@ 7g 175 ELE 1 Am E I Oct. 6,' 1931. H. E, KEwnTforq ET Ai. 1,326,178

GRINDING MACHINE Filed June 22, 1925 10 Sheets-Sheet 9 Patented Oct. 6, 193i 'UNITED STATES PATENT oFFlcE.

HERBEHTE. xEMrToN AND KEITH E. GALLIMCRE, or roND nu LAC, WISCONSIN, .AS-, SIGNCRS, BY lMESNE ASSIGNMENTS, To THE HEALn MACHINE COMPANY, or WORCESTER, MASSACHUSETTS, A CORPORATION oF MASSACHUSETTS GRINDING MACHINE Appiication mea June 22,

The invention relates to improvements in grinding machlnes, and is'hereln shown embodied in an internal grinding machine of `the type disclosed in U. S.Letter s Patent No. 4,534,302, issued April 2 1, 1925, to Prentice Conradson 'and ourselves.

- The machine disclosed in that patent comprises broadly, a. grinding spindle carriage having a grinding wheel, a headstock carriage last mentioned, position, and automatically 'for supporting the work, operating means for effecting a relative' reciprocation and a rela.- tive' cross feed between said carriages, and a gage adapted to coact with the work to control the grinding operation. In the operation, the grinding spindle carriage is automatically moved from a remote inoperative position to an operative position, reciprocated in said returned to said inoperative position whenthe work has been ground to a predetermined slze. The cross feedvis reduced as the grinding op- 'eration nears completion to provide a finishing cut,' 'and is subsequently discontinued when the work is ground to the predetermined size. `By a finis ng cut is meant the rela-V tively slow grinding during the latter part of the grinding operation for producing a smooth finish on the surface of the work. We have found that-an improved finish and other improved results are obtainedpif the speed at which the grinding spindlecarriage Y reciprocates is reduced forthe finishing out l*the iinshing cut;

An important object of the presentinvention;V

therefore, S t0 provide means automatic-all operable when the work is ground to a predetermined Size to slow down the rate of the of the 'grindingspindle carriage, which means is under the control of the gage, and serves on occasion to automatically by-pass a part 1925. Serial No. 88,629.

ot' the-hydraulic pressure luid normally directed to move said carriage.

lVe have alsofound that in withdrawing the grinding` wheel axiallyffrom the iinished surface of the work, marks and scratchesF are made near theend of the surface, thereby injuring the finish and lowering the quality of the product. Particularly is this true where cast iron is ground. and where the ground surface. is of considerable length.

Another object of the invention therefore is to provide means for automatically withdrawing the grinding wheel laterally from the surface of the Work before withdrawing the grinding wheel axially into its inoperative position.

A more speciicobject is to provide Va new and improved means'of the abovef character which is under the control of the gage, which is operated hydraulically, and which effects.

a lateral separation of .the grinding wheel and the finished work surface by shifting the cross feed screw longitudinally.

Other objects and advantages reside in the specific construction of the mechanical means Yfor''ccomplishing the above results.

A general object'of the invention is to providek an improved grinding machine which will produce an improved iinish'on the surface of the Work to be ground. Y

Furtherobjects and advantages 'will 'be' omeappar'ent as the description proceeds. n-theeaccompanying drawings, igure 1 embodying the features of our invention. Vlilig?, isa plan view of the machine. .Y FigIfBjisa vertical sectional view of the leadstock carriage taken along line 3-3 of 1g.2'.v Fig. 4 is a sectional view of the gage controlled switch taken along line 4-74 of Figl.

Fig. '5 is a sectional view of said switch' taken alongflineof Fig. 3. Fig. 6 is a vertical sectional along line 6-'6 of Figure 1.-

view `taken aifontside'viewof aj grinding machine Fig. 7 is a fragmentary sectionalviewof the main control valve and the Vactuator therej for.

Fig. Sis a sectional view of the valve taken i along` line 8-8 of Fig. 7.

l shown in Fig. 12.

- grinding operation 'has been completed.

Fig. 13 1s aplan view of the mechanism Fig. 14 is a sectional view taken along'line 14.-14 of Fig. 10.

Fig. 15 is a sectional view taken along line 15-15 of 4F ig. 10. Y Fig. 16 is-a diagrammatic representation of the hydraulicpsystem and of the electric circuits for operating and controlling the operation of the machinecarriages.

glo

' While the invention is susceptible of various modifications and alternative constructions and adaptations, we have shown in the drawings and will herein describe -in detail the preferred embodiment, but it is to be understood that we'do not therebyintend tolimit the invention tothe specific form disclosed, but aim in the appended claims to coverfall vmodifications and alternative constructions'.

and adaptations falling within the spirit and scope of the'invention.

`Referring now more particularly to the specific construction of the exemplary embodiment of the invention, the machine comprises a hollow base casting 17 having an internal' transverse -wall 18 which separates. the base into a side portion on which a head stock or headstock carriage 19 is mounted and a long bed on which a grinding spindle carriage 20 having a grinding wheel 21 1s mounted. Between the Wall 18 and another transverse wall 22 is a chamber adapted to contain a coolant luidfor the work, andi between the last mentioned wall and a third transverse Wall 23 is a reservoir adapted to contain a preure Huid, such as oil, for actuating the carriages 19 and 20.4

Hydraulic operating'mechanism is provided for effecting a'relative approaching movement between said carriages to bring them into operative relation, for automatically instituting and effecting a recigrocation of one of said carriages whilein sai operative relation, and for automatically eecting a sep,` arating movement of said carriages when the grinding bperation is completed. A feeding mechanism is also provided for effecting a relative cross 'feed between saidv carriages during the working 'reciprocation 'A gage coacting With the work being ground is operable to automatically eifect a reduction in the rate of cross feed for the finishing cut or operation and in the-speed of reciprocation during said cut, and is further operable to automatically discontinue the cross feed and lThe headstock carriage 19 (see Fig. 3) comprises a body section 24 which is slidably vmounted on transverse ways 25 on the machine base 17, and a top section 26 which is rotatably mounted in the body section and extends therethrough into the base. Journaled in t-he `top section 26 is a rotary work spindle 27 which carries a suitable chuck or Work fixture 28 on one end for holding the vwork to be ground, such' as the blank A, Vand which is driven through suitable connections including a clutch 29 by an electric motor 31 mounted on the underside of the top sectionv to move or rotate therewith. The clutch 29 is provided with a yoke 32 pivotally mounted on a rod 33 and having a depending arm 34. A cam 35 is rigidly mounted on a shaft 36 having a suitable operating handle 37, and is adapted to engage the arm 34 upon being actuated to throw the clutch 29..

The chuck 28 in the present instance is provided with a pluralityof clamping members 38 normally spring pressed into engagement with the work, and ada ted to be withdrawn therefrom by means o a suitable draw bar 39 operable by means of a hand lever 40.

'The gagz'ng mechanism ,and axially through the work spindle 27 into the' chuck 28, and having a pair of gages 42 and 43, designated respectively as a roughing gage and a linishing gage, mounted `on its forward end. The roufrhing gage 42 is slightly smaller in diameter than the finishing gage 43, and aI little in. advance thereof to permit the former to enter the bore of the blank A before the latter in the course of the grinding operation. The rear end of the gage rod 41 is connected by a bracket .44 to corresponding end of a parallel push rod 45 reciprocable in the topsection 26 and carrying an abutmentroller 46 at its forward end. A coil spring 47 engaging a collar 48 on the push-rod 45 tends to move the gages forward into yielding engagement with the inner edge'oithe bore in the blank A, and an adjustable abutment 4 9 on the grinding s indle carriage 20 is adapted to strike the ro 1er 46 to withdraw the gages from the work blank A as the grinding wheel 21 advances into the bore of said blank. When the bore has been ground toa predetermined size, the roughing gage only will enter -the bore, and when ground to the desired size, i. e. when the grinding operation is completed, both gages will enter. The gaging mechanism thus far described is fully disclosed in the Patent:

No. 1,534,302 hereinbefore referred to.

An arm rigidly mounted on the shaft 36 is adapted to engage a block 51 loosely mounted on the push rod 45 against the collar 48, and thereby to move the gages into inoperative position away from the work Y when the clutch 29 is thrown into open position to stop the spindle 27.

In moving initially past the inner edge of the work being ground, the gages 42 and 43 cause the successive closing of two switches 52 and 53 respectively. Preferably switches of the type disclosed in our U. S. Letters Patent No. 1,751,204, dated March 18, 1930, are employed. These switches are housed in a casing 54 secured to the left end of the body section 26 of the headstock car.- riage, and comprise two forked spring contacts 55 and 56 associated respectively with two sets of fixed contacts 57 and 5.8. The fixed contacts are supported on an insulating plate 59 over an oil reservoir 60 into lwhich the spring contacts 55 and 56 extend, and two of the fixed contacts, one from each set, are connected by a conducting plate 61 to which a common lead wire is attached.

The two spring contacts 55v and 56 are movably supported by a pair of tripping mechanisms 62 which at the beginning of the grinding operation are locked in inoperative position and which when released will move the contacts 55 and 56 into engagement with the fixed contacts. The tripping mechanisms comprise two trip dogs 63,y one for each mechanism, which are adapted to be engaged by a pair of plungers 64 slidably extending into the casing 54 and adjustably mounted in the bracket 44 fornm'ovement with the gages 42 and 43: These plungers are so adjusted that as the gage rod 41.is moved sufficiently to the right they will trip the two mechanisms successively to close the switches "52 and 53 in predetermined sequence.

The switches 52 and 53 after once being closed will vbe unaifected by the slight withdrawals of the gages from the work by the v abutment 49. A pin 65 carried by the push rod 45, which extends through the casing 54 betweenthe two tripping mechanisms, is adapted to reset both mechanisms, thereby opening the switches 52 and 53, when the clutch 29 is thrown into o pen position.

The grinding spindle carriage gitudinally on the base 17, and is provided with sides 66 overhanging the side walls of the base. i Rotatably mounted in the carriage 20 is a spindle 67 which carries the grinding wheel 21, and which is driven' by a beltv 68 from an elect-ric motor 69 mounted on the underside of the carriage to travel therewith.

The carriage is arranged to be reciprocated by a piston and cylinder unit, one element of which is mounted on the carriage to `travel therewith and the other element of which is rigidly mounted within the base. I n the present instance, the cylinder 70 is rigidly secured to the underside of the carriage 20, and the piston 71 is stationarily supported by hollow rods 72 having their remote ends mounted in the machine base. These rods communicate with the cylinder 70 at opposite sides of thepfston 71 to introduce and permit the escape of pressure fluid.

Hydraulic pressure fluid, preferably oil, is drawn from the oil reservoir in the machine base 17 by an oil pump 73 driven by an electric ,motor 74, said pump and said motor being mounted on the rear side of thebase. The oil is discharged from the pump 73 through a pipe 75 into the inlet port 76 of a\ main control valve 77 mounted on the front side of the base.` This valve is formed with ports 78 and 79 connected to the remote ends of the hollow piston rods 72 by pipes through the valve 77 can be varied to change the speed at which the carriage 20 moves by means of a hand lever 84 for adjusting a speed change gearing 85 in the connection between the motor 74 and the pump 73.

/ The valve member 83 is provided with a stem 86 pivotally connected to the lower end of an actuator which is inthe form of an upright lever 87 pivoted between its ends at 88 to the machine base. A pivotal dog 89 is mounted in the upper end of the lever 87, and is normally maintained in the path of vtwo dogs 9() and 91 by a spring follower 92. The dogs and 91 are adjustably secured to the front depending side 66 of the carriage 20 by bolts 93 engaging in a T-slot 94. The dog 90 is beveled-011 its lower left end to provide an inclined face which upon movement ofthe carriage from its inoperative position, shown in Figure 1, to the left will engage and depress the. pivotal dog 89 to permit the latterto snap .into position ,be- I tween the dogs 90 and 91. e Upon continued iso mov-ement ofthe carriage, the dogs 90 and i side of'the body Vsect-ion 2400i" thecarriage 91 will automatically oscillate the lever 87 to reciprocate the carriage in its operative position. The distance through `which the carriage will reciprocate 'will depend upon the spacing of the dogs and 91, and cor-v responds substantially to the length of the piece of work to be ground.

Mounted in a housing 96 on the base of the machine is an electromagnet 97 having a pivotal armature 98. A. pin 99 is secured to the free end of the armature 98, and is slidably mounted in the housing 96 in position to engage and depress the pivotal dog 89 when -the electromagnet 97 is excited. When the pivotal dog 89 is depressed, it will permit the dog 90 to, move past Without oscillating the lever 87, therebyA prolonging the outward stroke of the reciprocating grinding Wheel 21 Aso as to position the latter outside of the bore ofthe work. While the electromagnet 97 may be excited to effect this separation on any desired occasion, it is controlled in the present instance by the switch 53 adapted to be closed when the grinding operation is completed. The circuit through the: electromagnet 97 is as follows: Fromfthe positive terminal of the line through wire 100, 'the switch 53, wire 101, the electromagnet 97, and wire 102 to the negative terminal o f the line.

.To hold the dog 89 in depressed position after the excitation of the electromagnet 97, a catch 103 is adapted to fall -back of the pin 99 when the latter moves `forward. The catch 103 is provided with a pin or lateral projection 104which is adapted to lride upon an inclined cam face 105 on the inner end of the dog 90 to release the dog 89 when the grinding wheel 21^is separated from the work. A ca1n106 isadjustablymounted on'the carriage 20, and is yformed with a cam surface 107 adapted to engage the upper end of the lever 87 and move it into Vneutral position when the carriage 20. is moved into its inoperative position remote froinarrthe headstock carriage.

' Feeding mechanism-V .screw-10841:@ means, of the hand wheel 111,

The headstock carriage 19j be fed along the ways 25 to move the work blank A against the grinding wheel 21 means of a feed screw 108 mounted in the base 17 and engaging a nut 109 on the under (see Figs. 9 and 10). The outer end of the feed screw 108 extends through a feed box 110 on the front side of the machine, and is provided with a hand wheel 111 whereby itV may be manually rotated; v

Within the feed box, a ratchet wheel 112 is mounted on a slecve113 on the feed screw 108, and is connected through a train of gears 114 to' the screw. The ratchet wheel B5' 112 is adapted to be rotated intermittently by.

eitherone or both of two feed pawls 115 and 116. These awls are pivotally mounted on the opposite y extending arms of two bell crank levers 117 and 118, respectively, loosely mounted on the sleeve 113, and are resiliently held in engagement with the ratchet Wheel 112 by springs 119. The other arms of the bell crank levers extend horizontally side by side, and are provided with cams 120 on their lower sides adapted to be engaged by a lever 121 to reciprocate the pawls. The

degree of oscillation of these arms may be independently adjusted b means of two eccentrics 122 and 123 underlying them and limiting the downward movement of each of the cams 120. ln practice, the eccentrics 122 and 123 are so adjusted that the pawl 115, designated as the coarse feed pawl is given a relatively long reciprocation, and the pawl 116 designatedas the fine feed pawl is given a relatively short reciprocation. I

-The lever 121 is oscillated by means of a floating piston 124 reciprocable in a' stationary horizontal cylinder 125. Pressure lluid is successively and alternatively received by and discharged from opposite ends of the cylinder 125 through pipes'126 and 127 branching from the pipes 80 and 81, respectively.

Mounted in thefeed box 110 are a pair of electromagnets 128 and 129 provided with armatures 130 and 131 yhaving curved tracksv 132 and 133 respectively. The latter underlie rollers 134- and 135 on the pawls 115 and 116, and upon excitation of the electromag- -nets will raise the corresponding pawls out ,128,Vand through the switch 53, the wire 101,

and the electromagnet 129 to the wire 102 and .negative terminal. Since the switches 52 and 53 close in Sequence, the electromagnets will be closed in succession to automatically re- ;1 Vduce land finally discontinue the cross feed as theV grinding operation progresses.

To-fpermit manual operation of the feed the pawls 115 and 116,v after excitation of the elegtilomagnets are automatically locked in inoperativeposition by a pair of latches 137 Vengaging the heels of the armatures 130 and 1131. The latches 137 are mounted on a pair of shafts 138 together with releasing levers 139 which are connected by suitable linkage 140 and which can be oscillated simultaneously by a lever 141 to disengagesaid latches and thereby release the pawls;

'The .slow tra/verse mechanism .To obtain a .relatively slow traverse of the grinding wheel 21 in its working reciprocation during the finishing out, a part of the pressure fluid normally paing through the main controly valve 77 is upon entry of the kgage 42 into the bore of the work automatically by-passed to the oil reservoir in the base. To this end, the supply pipe 75 is -connected With a pipe 142 which leads to a hollow casing 143 mounted in an opening 144 in the ront'wall of the machine base (see Fig. 10). The' casing 143 is formed with an inlet passage 145 and an outlet passage 146, said passages communicating respectively through ports 147 and 148 with thel interior of a valve sleeve 149. Opposite ends of the sleeve 149 open into an exhaust cham-ber 150 having an' exhaust pipe 151 leading to the oil reservoir in the base. A pair of plugs 152 are. removably threaded into opposite ends of the casing143 in alinement with the valve sleeve 149.

eciprocably mounted in the sleeve 149 is valve member 153having a pair of spaced enlargements 154 controlling the ports 147 and N148. The valve lmember is provided with a,

stem 155 extending slidably through the invthe ports 147 and 148 so as toby-pass a part of the pressure fluid normally passing to the main valve 77. A coil spring 158 on the stem 155fbet'ween the plug 152 and the rarmature 156 tends to cut oil3 the ports 148 from the ports 147, and serves to return the valve mem ber 153 to itsinitial position when the elect-romagnet 157 is deenergized.

As the grinding spindle carriage reciproc'ates, its movements are opposed.V by a variable resistance. Thus, at the end of its.

' inward stroke, the carriage assumes the added burden of moving the gages 42 and 43 away from the work. These changes in resistance result in a change of the pressure of the luid 1n the cylinder 70, which tends to vary the speed of the carriage by causing unequal volumes of pressure liiuid to be shunted through the' pipe 142. To maintain a constant o arriage speed, a self adjusting valve (see Fig. 15) is provided inthe outlet passage 146. :This valve comprises a cylinder 159 threaded into the wall of the casing 143 and". having o ne or more ports 160 opening into the exhaust chamber 150. A piston 161 is slidably mounted in the cylinder 159 and is formed with a central passage 162 opening intothe outletpassa'ge 146 and communieating through ports163 with the ports 160. Movement of the piston 161 is controlled and limited by a pin 164 mounted therein and engaging a slot 165 in the cylinder 159. The

slot 165 extends along the outside of the cylinder 159 to the exhaust chamber 150, and permits iiuid from the cylinder to be exhausted When the piston 161 moves to the left. -A sleeve 166 is threaded onto the front end of the cylinder 159, and is closed by a plug 167.`

Threaded into the sleeve 166 is an adjusting nut 168 between Which and the inner end of the piston 161 a coiled spring 169 is positioned to counterbalance 'the pressure required to move the carriage at a predeterminedspeed. The ports 160 and 163 normally are in full register to provide the largso Y est possible openings between the outlet pas- Y sage 146 and the exhaust chamber 150. If the pressure increases, the piston 161 will move the ports 160-and 163 partly out of register to reduce kthe eHective area of the openings therethrough. If the pressure is reduced',the

piston 161' will move to the ,right to enlarge v the openings through the ports 160 and 163. The valve thus permits a constant volume of pressure Huid to pass into the. exhaust chamber 150 independent of the pressure, and consequently causes the carriage to move at a uniform speed irrespective of changes in the resistance opposing'its movement.

The back-077 mechanism According to our invention,'the grinding Wheel 21 andthe finished work surface are to be slightly separated laterally when the grinding is completed, and when the grinding lwheel is about to be separated longitudinally from the work. While either of the carriages 19 and 20 may be' moved to effect this separation, preferably the headstock carriage 19 is shifted through the feed screw 108 by a back-off mechanism (see Figs. 10 to 14) controlled by the gage 43. This mechanism comprises a pairof collars 170 mounted on the feed screw 108 next to a shoulder 171, and separated by a spacer 172. The collars 170 are held in place by a spacer sleeve 173 positioned between the front collar andthe sleeve 113 in the feed box. Mounted on the spacer 172 between the collars 170 isa yoke 174 having two lateral cylindrical extensions 175 which are pivotally mounted inthe arms of a bifurcated head 176 on the upper end of a-lever 177. The head 17 6 is pivotally supported on a pin 178 in a bracket 179 rigidly secured to the base 17. The bracket 179 is formed integral with a water guard 180 which is also secured to the base 17 and which overlaps with a Yshield 181- on the headstock carriage 19 to protect the parts underneath.

The lower end of the lever 177 is formed with a knob 182 which engages in a milled slot 183 in a reciprocable piston 184. The pistonis mounted in a cylinder 185 formed ir the casing 143 and closed at its opposite ends by plugs or caps. 186 having stops18`7 formed thereon. A pocket 188 is formedin 'the casing 143 over the slot 183 to receive pressure fluid leaking pastthe ends of the piston, and a drain pipe 189 serves to return the fluid from said pocket to the oil reservoir. The position of the piston is cont-rolled by a valve comprising a valve sleeve 190. This sleeve is formed with a set of central ports 191 communicating with the inlet passage 145', and two sets' of end ports 192 and 193 communicating with passages 194 and 195 leading to opposite ends of the cylinder 185. The opposite ends of the sleeve 190 open into the exhaust chamber 150. End plugs 196 are threaded into opposite ends of the casing 143 in line with the sleeve 190. l

Reciprocably mounted in the valve sleeve 190 is a valve member 197 having two enlargements 198 adapted upon recipnocation to successively and alternately connect the end ports 192 and 193 with the exhaust chamberv 150 and the inlet ports 191. The member 197 is provided with a stem 199 which eX- tends slidably through one of the end caps 196, and t-he free end of which is pivotally secured to the free end of the pivotal armature 200 of an electromagnet 201. The electromagnet 201 is rigidly supported on the casing 143, and the circuit therethrough is as follows: from the positive terminal through the wire 100, the switch53, the wire 101,- the electromagnet 201, and the wire 102 to the negative terminal. A coil spring 202 on the stem 199 between t-he armature 200 and the end cap 196 tends to maintain the valve member 197 to the right to connect the ports 191 and 193. gage 43 moves past the inner edge of the finished work surface, thereby closing its switch 53, the electromagnet 201 will be excited, and will cause the feed screw 108 to be shifted longitudinally to the left to separate the grinding wheel 21 and the finished work surface.

The operation The operation of the machine will be evide nt from the foregoing description, and briefly stated is as follows: The work to be ground is placed in the chuck 28, and the lever 37 is actuated to throw in the clutch 29 and start operation of the spindle 27. By actuating the lever 37, the cam 50 releases the push rod 45,'thereby permitting the gages 42 and`43 to move into engagement with the inner 4end of the work. The lever 87 at the front of the machine base 17 is thrown to the right thereby'instituting movementof the grinding spindle carriage 20 to the left.

When the grinding wheel 21 has reached the work, the dog 90 will depress'the pivotal. dog 89 and cause the latter to be positioned between the dogs 90 and 91 to institute'and eil'ect an automatic reciproca-tion of thev wheel in its operative position. At the ini-*11:41 is far withdrawn, thereby opening the It will be evident that when the' into communication.

rocate and the headstock carriage to be fed' transversely of the grinding Wheel until the `work is ground to a predetermined size whereupon the foremost gage 42 will move past the inner edge of the surface being ground. This action permits the age rod 41 to move forwardly a distance su c1ent to close the switch 52.

Closure f the switch 52 results in the excitation of the electromagnets 128 and 157. The electromagnet 128 raises the pawl 115 and effects a reduction in the rate of cross feed. The electromagnet 157 simultaneously moves the valvev member153 to bring the ports 147 and 148 into communication with each other, thereby by-passing a part of the pressure fluid normally passing to the main control valve. IAs a result the speed of the grinding spindle carriage 20 is reduced during the linishing cut. The speed of the carriage20 is maintained constant bythe self adjusting valve in the outlet passage146.

When the Work has been ground to the Y desired size, the second gage 43 will move past the inner edge of the finished work surface thereby permitting the gage` rod 41 to move forward sufficiently to close the switch 53. Closure of the last mentioned-switch simultaneously closes the circuits through the electromagnets 129, 201 and 97. Excitation of the first electromagnet raises the l feed pawl 116 to discontinue the cross feed.'

Excitation of the second electromagnet y201 causes the movement of the valve member 197 to the left to bringDthe ports 191 and 192 ressure Huid is thereupon directedto the outer end and from the inner end of the cylinder 185 to move the piston 184, thereby shifting the feed screw 108 longitudinally a small distance to the l'eft. This causes a lateral separation of the grinding wheel 21 and the finished work surface. Excitation of the third electromagnet 97 results" in the tripping of the dog 89 to permit a prolongation of the outward stroke of the grinding wheel. Since the grinding wheel is now separated from the finished work surface it will pass beyond the work without engaging said surface. l

When the grinding wheel 21 rhas been withdrawn longitudinally just beyond the work, the clutch 29 is thrown out to stop the spindle 27 and permit reloading of the chuck. In opening the clutch, the gage rod switches 52 and 53, and resetting the trip ing mechanisms 62 therefor. Openingof t ese switches causes all of theelectromagnets to be deenergized'. Thereupon the springs 158 and .202 move the valve members 153 and 197 to the right s o as to close the by-pass valve andshift the feed screw 108 back to initial position. The grinding spindle carriage then continues to4 move at fast speed toward its inoperative position in which it is automatically stopped by the cam 106.

After the chuck 28 has been reloaded, the above operation is repeated. I,

By slowing down the speed o'f reciprocationbf the grinding 'wheel during the linislination,A a carriage having a. grinding wheel,

a lieadstock adapted to support the work ,a gage arrange-d to coact with the work, hydraulic operating means for eti'ecting a relative working reeip'roeation between said grinding wheel and said work, means -set in operation by said gage for prolonging one stroke of said reciprocation te separate said grinding wheel 'and said work in one direc tion, and means set in operation by said gage vfor automatically ei'eeting'a separation be-v tween said grinding wheel and said work in Hl i another direction to permit said first mentioned separation without permitting said grinding wheel to engage the end o'f the ground surface. l

2. A grinding machine having, in combination` a carriage having a grindingwhecl,

a headstock adapted to support the work, a'

gage arranged to coact with the work, means for effecting a relative intermittent approach- -ing movement, a. relative reciprocation and a separation at the completion/0f said reciprocation between said grinding wheel and the work, said separating movement being instituted by said gage, means set in operation by said gage for slowing down the speed of said reciprocat-ion during the last part of the i grinding operation,

[surface before said tion by' said gage' for effecting a separation between said grinding wheel and the work first mentioned separation between 'said grinding wheel and the,` work is completed.

v3. A grinding nation ,a.V grinding wheel, a headstock adapted to support the work t0 be'ground a car riage sup-pprting one of said parts, `fluid pressure means and means set in operamachine having, in combi# y for moving said carriage and?Y P thus relatively reciprocating said grinding '-j 'wheel axially across the surface of said work,

mea-ns .automatically operable when the grinding has proceeded to a predetermined point to slow down the speed` of said reciprocation, and self adjust-ing means for changf ing the pressure of tlieiuid to compensate for changes in the resistance to said`recipi'o-- eatingY movement, said last mentioned means serying to maintain a constant speed'during the slowv reciprocation.

4. A grinding machine having, in combi! nation, a grinding` wheel, a headstock adapt- 'ed to support the work to be ground, a earriage supporting one of said parts. fluid pressure means for reciprocating saidv carriage and thus effecting a relative reciprocation ot' said grinding wheel with respect to the work,

and means for slowing down the speed of i'ecipi'ocation,"L said last mentioned means including means for maintaining a constant speed of said reciprocation after the latter is reduced. f

5. A grinding machinel having, iireombination, a carriage having a grinding wheel, a headstock for supporting a workpiece, for the grinding of a bore therein by said wheel, iuid pressure operating means for producing aV relative axial reciprocation between said wheel and the workpiece bore in the grinding of the latter, a gauge arranged to enter said 'workpiece bore when the grinding thereof has proceeded to a predetermined point, and a by-pass valve controlled by said 'i gage and adapted to by-pass`a portion of the ressure uid -normally directcdto said operating means when the grinding has proceeded to said predetermined point, thereby to slow down the speed of said reciprocatioin 6. A grinding machine ha-ving,'iii combination, a carriage lia-ving agrinding wheel,

a lieadstock adapted to support the .work to' be ground, a gage arranged to c'oact. `with the work, hydraulic operating meansv for eifectin g an approaching movement between said grinding wheel andthenvork to bri-'ng them into operative'relation, a relative reciprocating movement therebetween axially-of vsaid grinding wheel, and an automatic separation therebetween axially of said grinding'wheel when the work has been ground to a prede'- termined point, means automatically operable to by-pass a pa-rtof the pressure fluid directed to cause said ,above movements to slow down said reciprocation'when the grinding has progressed to a predetermined point, said llast mentioned means including -means for maintaining a c onstant speed of reciproeation irrespective of variations in the pressure of said pressure Huid.

7. A. grinding machine having, in combination, a carriage having a grinding wheel, a lieadstock adapted to support the work, means for eectingfa relative intermittent cross feed between said Agrinding wheel and said work, means for eiiecting a relative movement axiall of said grinding wheel between said grindling wheel and said Work to grind the latter and for automatically separating them axially of said grinding wheel, said separation occurring only at the completion of the grinding operation,means, automatically operable to successively reduce the magnitude of individual crossfeed actuations and discontinue said cross feed, and means automatically operable atthe completion of the grinding operation to effect a lateral separation between said grinding Wheel and the work in the direction of said cross feed to permit the first mentioned separation of the grinding wheel and the work without engagement of said grinding Wheel 'with the finished work surface.

8. A grinding machine having, in combination, a carriage having a grinding wheel, a headstock adapted to support the work, means including a feed screw for moving uwsaid headstock transversely 0f Said grinding fifi wheel to effect a relative feeding movement between said work and said grinding Wheel, means for effecting a relative movement axially of said grinding wheel and the work, and means automatically operable to shift said feed screw bodily and longitudinally tov effect a lateral separation between said grinding wheel and said work.

9. A grinding machine having, 1n combination, a carriage having a grinding' wheel, a'

headstock carriage adapted to support the work, means for moving said grinding wheel and said work relative to each other to grind the latter, one of said carriages having a Cross feed screw, a lever rotatably engaging said cross feed screw, means automatically operable when the grinding has proceeded toV a predetermined point to oscillate said lever and shift said feed screw bodily thereby effecting a separation between said grinding wheel and said work laterally of. said grinding wheel.

10. Agrinding machine having, in combination, a support for a grinding Wheel, a support for the work to be grour d, means for effecting a relative movement between said grinding wheel and said work to grind the latter, a gage arranged to coact with the work, a piston and cylinder unit, a lever engaging one of `said supports at its upper end, and one of the elements/of said piston and cylinder unit at its lower end, and means under the control of said gage for directing pressure fluid to said piston and cylinder unit to yoscillate said lever and thereby shift said grinding wheel and said work laterally relatively to each other to separate them.

11. A grinding machine hav-ing, in combination, a carriage having a grinding wheel,

. a carriage for supporting the work, said earriages being mounted for a relative crossfeed, a gage arranged to coact with the work, a lever engaging one of said carriages and adapted to move the same in the line of said cross-feed, a piston and cylinder unit for actua-ting said lever to shift said last mentioned carriage, a valve for controlling the admission of pressure fluid to said piston and cylinder unit, and an electromagnet controlled by said gage for actuating said valve.

12. A grinding machine, having in combination, a carriage having a grinding wheel, a carriage for supporting the Work, hydraulic operating means for effecting a relative reciprocation between said grinding wheel and said work axially of the grinding wheel, a gage arranged to coact with the work, a bypass valve for by-passing a portion of the pressure fluid normally passing to said operating mechanism, and an electromagnet controlled by said gage for actuating said valve to by-pass said pressure Huid and effect a reduction in the speed of said reciprocation.

13. A grinding machine having, in combination, a carriage having a grinding wheel, a carriage for supporting the work, means for effecting a relative reciprocation between said grinding wheel and said Work axially of the grinding wheel, intermittently operated means for feeding said carriages one in relation to theother, so that the grinding wheel will make successively deeper cuts in the work, said means being brought into operation substantially at the reversals of the aforesaid `reciprocating movements, autoi matic means for causing ultimate separation of said carriages 'in a direction parallel to the axis of said grinding wheel, whereby to draw said grinding wheel by the edgeof a workpiece being ground, and further automatfc means brought into operation only upon operation of lsaid first-mentioned automatic means, to cause separation of said carriages in a rdirection substantiallv at right` angles to the axis of the grinding wheel, whereby to removel said wheel from contact with a workpiece before any part of said wheel moves past the edge of said workpiece, during the movement of axial separation of said carriages. l

14. A grinding machine having, in combilll) nation, a grinding wheel, a head stock, means for procuring a relative reciprocating motion of one of said parts in relation to the other through a given range of travel, and for causing a movement of separation between them along the direction of the aforesaid i range of travel but beyond it, means governed by the progress of the grinding operation, means set in operation by said last namedgmeans to procure the said movement of separation, and further means also set in operation by the means governed by the Yprogress of thel grinding operation to procure a lateralV 'separation between, the grinding wheel and the head stock, on a line divergent fromthe aforesaid line of travel,

and before the aforesaid movement ofse'paration on said line, whereby to procure automatic determination of a grindingl operation and separation between a grinding wheel and workpiece without running the wheel oif the tion of said carriage, means governed by the progress lof a grinding operation to automatically Vbring into operation said controlling means, and means coincidently brought into operation Afor varying the ,pressure of the fluid, during the slow reciprocation vof the carriage, to compensate for changes of resistance to movement of said carriage. l

V16. In a grinding machine, a head stock adapted to hold a workpiece, a grinding wheel, means for reciprocating said grinding wheel relative to the work to produce a grinding traverse through a given range and for withdrawing said grindlng wheel relative to the work in lan axial direction to separate them, work sizing means to set 1n operation the withdrawal movement axially, cross feeding mechanism to feed the workpiece in cutting relation to the grinding wheel, means to eifect a lateral separation between the work and wheel, and controlling means operated by said worklsizing mechanism for causing said lateral`separation to c take place beforev thegwheel has left the workpiece. v

17. In `a grinding machine, ahead stock adapted'to holdV a workpiece, a' grinding wheel, means for reciprocating said grinding Y wheel relative to thework to produce" a grinding traverse through a given range and for withdrawing said grinding wheel relative to the work in an axial direction to separate them, work sizing means to set in operation the withdrawal movement axiallg, cross feeding mechanism to feed the wor piece in cutting relation to the grinding V wheel, means-additional to said cross feeding means to effect-a slight lateral separation along the line of the/ cross feed between the workA and wheel, and ,controlling means operated by said work sizing mechanism for ca before/the wheelhas left the workpiece.

18. a machine, thecmllbination"with a /wheelLaZ-workheam a YVIreciprocatory tableJ orfproducing a relative for eectng a emes feed of one of saidparte axial traverse between said parts, and mall.

relative to the other, of automatic means for causing said table to move beyond its normal traverse, to substantially separate said wheel and workhead along the line of said reciprocation, and means responsive to said automatic means for causing said wheel and workhead to separate along the line of said cross feed.;y n

19. In a grinding machine, the combination with a grinding wheel, a workhead, a reciprocatory table for producingfa relative axialtraverse between said parts, and means for effecting a cross feed of one of said parts relative to the other, of automatic means fol;l causing said table to substantially separate said wheel and workhea'd along the line of said reciprocation, and hydraulic means rea sponsive to said automatic means for causing a separation of said wheel and workhead along the line of said cross feed.

20. In a grindin machine, the combinawhen actuated, to cause said Workhead and d wheel to separate along the line of said cross;

feed, and hydraulic means brought into operation coincident with said automatic means to actuate said other means f 21. In a grinding machine, 'a table or car-- riage, meansV for giving said table or carriage a reciprocatory motion, a cross slide, a cross feed screw adapted, when turned, to eifect a progressive cross feed movement 'fof said cross slide relative to said table or carriage transversely tothe line of the lattersfreciprocation, automatic means for extending thereciprocatory motion of said tableor car-- inding wheel, aworkhead,

riage, and -means responsive thereto for i eifecting a retraction of the cross feed movement of said slide relative to said table or carriage without turning,Y said cross feed screw. z

In testimony whereof we have hereunto aliixed our signatures.'

HERBERT E. KEMBTON.. -KEITH F. GALLIMQRE.

said lateral separation to take place 

